OBJECTIVE: The overall objective of the Children's Cancer Study Group is to improve the treatment of childhood cancer through controlled clinical trials of newly-developed therapies and combinations of therapeutic modalities carried out by multidisciplinary investigative teams at leading pediatric centers across the U.S. and Canada. The CCSG is an organization of pediatricians, radiotherapists, pathologists, immunologists and statisticians who are experienced in the clinical and research aspects of cancer in children. It was established to study factors which may cause or influence cancer and to develop, evaluate and improve methods of treatment. APPROACH: The basic premise of group cooperation in clinical investigtion is that by pooling the experience of a large number of investigators new information may be acquired and advances made more rapidly than by the independent efforts of each. A new concept or a new therapy may be examined critically on a large number of patients far more quickly than would be the case if each investigator were studying only his own smaller number of patients. Through this multidisciplinary, cooperative group mechnism, the CCSG enters pediatric patients from participating member institutions onto clinical trials protocols. Each patient, regardless of the institution of origin, is entered on study, followed through the course of treatment and evaluated through a centralized Operations Office consisting of the Chairman's Office, Statistical Office and Data Center. Patient data, interim reports and study results are regularly fed back to the participating institutions and study committees, and final reports are published in the medical literature.